Diagnosis Of Microadenoma Research Articles

Precontrast T1 signal measurements of normal pituitary and microadenoma: A retrospective analysis through DCE MRI signal time curves.

Background:The dynamic contrast enhanced magnetic resonance imaging (DCE MRI) has currently become the most utilized technique for the detection of pituitary microadenoma. However, owing to differential enhancement of normal pituitary, high rate of false positivity remains a concern in its interpretation.Purpose:Our aim was to assess the utility of precontrast T1 signal intensity ratio (SIR) of the lesions suspected on DCE MRI, in prediction of presence of microadenoma.Materials and Methods:We retrospectively reviewed MRI of 23 patients referred for DCE MRI of pituitary (group 1, 15 patients with diagnosis of pituitary microadenoma; and group 2, patients not clinically labeled as microadenoma). STC were plotted and T1-SIR at t = 0 s was obtained at the suspicious zone of differential enhancement (SIR T) and normal pituitary (SIR P). SIR difference (SIR P − SIR T) and relative SIR difference (SIR P − SIR T/SIR P) were calculated for each patient and was compared between the two groups.Results:Mean T1 SIR is lower in patients with microadenoma than those without (P = 0.065). SIR difference and relative SIR difference was higher in patients with microadenoma (P = 0.003 and 0.005, respectively). Receiver-operated characteristic curve analysis demonstrated that a cut-off of 26 and 0.107 for SIR difference and relative SIR difference, respectively, could diagnose microadenoma with 100% specificity and reasonable sensitivities.Conclusion:The baseline precontrast T1 SIR evaluation of the lesion suspected to be microadenoma on DCE MRI, derived through STC curve, can increase diagnostic confidence in diagnosis of microadenoma.

High-Resolution DCE-MRI of the Pituitary Gland Using Radial k-Space Acquisition with Compressed Sensing Reconstruction.

The pituitary gland is located outside of the blood-brain barrier. Dynamic T1 weighted contrast enhanced sequence is considered to be the gold standard to evaluate this region. However, it does not allow assessment of intrinsic permeability properties of the gland. Our aim was to demonstrate the utility of radial volumetric interpolated brain examination with the golden-angle radial sparse parallel technique to evaluate permeability characteristics of the individual components (anterior and posterior gland and the median eminence) of the pituitary gland and areas of differential enhancement and to optimize the study acquisition time. A retrospective study was performed in 52 patients (group 1, 25 patients with normal pituitary glands; and group 2, 27 patients with a known diagnosis of microadenoma). Radial volumetric interpolated brain examination sequences with golden-angle radial sparse parallel technique were evaluated with an ROI-based method to obtain signal-time curves and permeability measures of individual normal structures within the pituitary gland and areas of differential enhancement. Statistical analyses were performed to assess differences in the permeability parameters of these individual regions and optimize the study acquisition time. Signal-time curves from the posterior pituitary gland and median eminence demonstrated a faster wash-in and time of maximum enhancement with a lower peak of enhancement compared with the anterior pituitary gland (P < .005). Time-optimization analysis demonstrated that 120 seconds is ideal for dynamic pituitary gland evaluation. In the absence of a clinical history, differences in the signal-time curves allow easy distinction between a simple cyst and a microadenoma. This retrospective study confirms the ability of the golden-angle radial sparse parallel technique to evaluate the permeability characteristics of the pituitary gland and establishes 120 seconds as the ideal acquisition time for dynamic pituitary gland imaging.

State of art imaging of the pituitary tumors

Over the years imaging of the pituitary has passed through different stages of evolution. Currently magnetic resonance imaging (MRI) is the modality most often used in studies of the pituitary gland. The role of computed tomography (CT) scanning is only appropriate to address specific questions in evaluating abnormalities within the pituitary gland. CT is used more often in lesions located in the parasellar and suprasellar regions or in the bones at the base of the skull. There are various issues that need to be addressed when dealing with the possibility of pituitary dysfunction. Biochemical tests and the clinical symptomatology are indispensable in the diagnosis of a hormonal abnormality that may have its origin in the pituitary but such tests are not always conclusive. Adenomas in the pituitary are benign lesions that cause hyper secretion of a hormone. In order of descending frequency we encounter prolactin (PRL), growth hormone (GH), adrenocorticotrophic (ACTH), gonadotrophic (FSH, LH) and thyrotrophic (TSH) secreting adenomas. The role of imaging is not to distinguish one type of adenoma from the other but to document the presence of the lesion, to show its exact location within the gland and to estimate its size. Adenomas can be small lesions imbedded within the pituitary gland or large enough to increase its size. The terms of microadenomas and macroadenomas have been adopted to describe lesions smaller or larger than 10 mm. The diagnostic issues in these two types of adenomas are different. The main problem in the case of small tumors which may measure 2–3 mm in diameter is that of detection. Small adenomas can easily escape detection because they often enhance in a fashion similar to normal pituitary. Also, the appearance of such small tumors is subjected to the effects of averaging in tomographic sections of 3 mm thickness. Depending on the histologic type, adenomas can be treated medically or by surgical excision. Prolactinomas, at least initially, may be treated medically, whereas the treatment for most of the other adenomas is surgical excision. Targeted radiation therapy is also used in cases that cannot be surgically resected or in patients with incomplete resection of the tumor. Pituitary adenomas selected to be treated by surgery are often small when first diagnosed and yet produce profound clinical symptoms. Therefore detection of small adenomas by imaging is critical for surgical planning. It has been shown that when imaging has accurately identified the adenoma within the pituitary the rate of cure is 80–90 %. When the diagnosis of microadenoma is ambivalent or incomplete, the rate of cure after surgery drops to 50–70 % [1–3]. Adenomas are usually round space occupying lesions commonly separated by a pseudo capsule from the normal pituitary. Even when a pseudo capsule is formed, the border of the adenoma and its interface with the pituitary parenchyma may not be well defined by imaging. This leads to underestimation of its size, which in turn, can result in an incomplete surgical excision and recurrent symptoms. Another diagnostic problem is encountered when the adenomatous mass occupies the entire sella without increasing the overall size of the pituitary. Then the adenoma is not clearly separated from the normal pituitary and may be mistaken as a normal gland. In other instances there is no discreet mass within the pituitary but instead there a diffuse infiltration of its parenchyma by hypersecreting cells [4]. Both the above abnormalities are not detected preoperatively by imaging and may not be appreciated even during surgery. The correct diagnosis is N. J. Patronas (&) C.-Y. Liu Bethesda, MD, USA e-mail: npatronas@nih.gov

Diagnostik des hypophysären Mikroadenoms

Radiologic diagnosis of microadenomas of the pituitary gland is challenging since the pituitary gland is a very small-volume organ in close neighbourhood to many eloquent structures. Furthermore imaging necessitates high contrast and topographic resolution not to miss the often very subtle microadenomas.[nl]Magnetic resonance imaging is the modality of choice providing multiplanar high contrast images of the pituitary gland and its adjacent structures. Special techniques like dynamic contrast enhanced imaging of the pituitary gland and bilateral inferior petrous sinus sampling are additional techniques to localize microadenomas. Additionally, anatomic variations can aggravate differential diagnosis.

IRM et adénomes hypophysaires

Pituitary is the most important gland of the organism which can be affected by many diseases, especially by adenomatous processes. Classically macroadenoma, microadenoma and picoadenoma are described, according to the size of the pituitary adenoma. The diagnosis of microadenoma was long considered a highly difficult task and that of picoadenoma was impossible by computed tomography. Recently, the high resolution of multiplanar MRI has enabled the diagnosis of microadenomas measuring less than 3 mm (picoadenoma). For macroadenoma, MRI not only contributes to diagnosis but is particularly important to assess the extension and to detect possible complications. The aim of our study is to illustrate MRI features in pituitary adenoma.

Effect of TRH on beta-gonadotropin subunits in patients with pituitary microincidentalomas.

To explore the hypothesis that most of the pituitary abnormalities compatible with the diagnosis of microadenoma, and detected in about 10% of the normal adult population, represent asymptomatic gonadotropinomas. Patients diagnosed with pituitary microincidentalomas at the Institute of Endocrinology of the Tel Aviv Medical Center were evaluated. Circulating beta-subunits of gonadotropin hormones were measured before and 30, 45, 60 and 90 min after the intravenous injection of 400 microgram TRH. Twenty-two patients with pituitary incidentaloma and 16 normal volunteers were tested. In 16 of the 22 patients, an abnormal beta-subunit response was detected after the TRH challenge. Three patients had an abnormal increase in both beta-FSH and beta-LH after TRH administration. Isolated pathological beta-FSH or beta-LH responses were demonstrated in five and eight patients respectively. Six patients had normal basal and stimulated gonadotropin subunit values, raising the possibility that their lesions were not pituitary microadenomas. There was a significant overall difference between the response to TRH of the patient and control groups. In the gonadotropin positive group, comprising 16 patients, serum beta-FSH increased from 6.4+/-1.6 ng/ml to 9.2+/-1.3 ng/ml (P=0.042) 1 h after TRH stimulation, whereas no changes were detected in the control group after TRH injection (basal: 4.1+/-0.8 ng/ml, peak: 5.1+/-0.8 ng/ml; P=0.15). Serum beta-LH increased from 10.5+/-3.2 ng/ml to 23.4+/-4.9 ng/ml (P=0.0037) at this time, in contrast to a lack of response in controls (basal: 6.4+/-1.5 ng/ml, peak: 8.2+/-2.3 ng/ml; P=0.24). In about 73% of patients with pituitary incidentalomas smaller than 10 mm, TRH elicits an increase in gonadotropin beta-subunits. This observation raises the possibility that non-functioning pituitary micro- and macroadenomas, which share a similar response to TRH, originate in a common ancestor cell type, probably a pituitary gonadotrope.

Gd-DTPA in clinical MR of the brain: 2. Extraaxial lesions and normal structures.

Fifteen patients with suspected extraaxial tumors were evaluated with MR before and after intravenous injection of Gadolinium-DTPA (Gd-DTPA). Meningiomas (7), neurinomas (4), chordomas (2), a previously irradiated dural metastasis, and a giant aneurysm were studied. All the lesions except the dural metastasis enhanced. In two patients with asymptomatic meningiomas, the use of Gd-DTPA with MR allowed definitive diagnosis of the lesions when the routine MR did not. Gd-DTPA also provided improved definition of intracranial tumor margins, produced differential enhancement of dura and nasopharyngeal mucosa from tumor, and caused enhancement of the choroid plexus, some venous structures, the pituitary gland, and its stalk. The enhancement of the pituitary suggests a role for Gd-DTPA in the diagnosis of microadenomas. Routine T2-weighted images without Gd-DTPA were useful in differentiating neurinomas from meningiomas. Judicious use of Gd-DTPA should improve the ability of MR to detect extraaxial lesions, delineate their extent, and characterize their perfusion.